Wastewater treatment system and method

ABSTRACT

The wastewater treatment system provides multiple techniques for decontaminating wastewater contained within a single system, thus optimizing the decontamination of the wastewater. In one embodiment, the wastewater treatment system includes a steel-reinforced plastic tank having first and second partition walls dividing the tank into first, second and third chambers. The first chamber includes at least one first effluent filter and further contains anaerobic bacteria for removal of organic waste material from the wastewater received therein. The first chamber is configured for at least partial removal of particulate and organic matter from the wastewater. The second chamber includes an air diffuser and further contains aerobic bacteria for further removal of organic waste material from the wastewater received therein. The third chamber includes a sludge pump assembly and at least one second effluent filter. Resultant purified water is selectively discharged from the third chamber through an outlet port.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/282,281, filed Jan. 13, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to water supply treatment systems, andparticularly to a wastewater treatment system and method that removesbiodegradable fats, oil, grease, solids, organic contaminants,nutrients, pathogens and the like from wastewater generated inresidential homes, commercial businesses, industrial facilities,municipal facilities, agricultural facilities and the like.

2. Description of the Related Art

In order to protect the environment and promote public health,communities typically require wastewater treatment. The discharge ofuntreated wastewater is not suitable, since it gives rise to numerousenvironmental concerns, such as the pollution of surface and groundwaterresources. Untreated wastewater contains organic matter and nutrientsthat, if left untreated and not removed from the waste stream, canresult in environmental pollution. Thus, when untreated wastewater isreleased into either aboveground bodies of water or subsurfacedrainfields, the level of dissolved oxygen in the receiving watersbegins to deplete, which endangers the water bodies themselves, alongwith the resident plant and aquatic life. Additionally, in developingnations, where potable water is scarce, it is often desirable to recoveras much reclaimable water as possible from wastewater, rather thandisposing of both the wastewater and the contaminants.

To treat wastewater, communities in highly populated areas commonlycollect wastewater and transport it through a series of undergroundpipes to a large, centralized wastewater treatment plant. However, thereare several problems associated with large, centralized treatmentplants. Centralized wastewater treatment plants are designed and ratedfor processing a specific flow rate of wastewater per day, typicallyexpressed as the rated capacity of the plant, and all treatment plantshave a maximum flow rate capacity. Thus, if a centralized treatmentplant receives more wastewater on a particular day than what the plantwas designed to handle, problems are encountered. For example, when atreatment plant receives larger-than-normal amounts of untreated rawwastewater, treatment performance decreases and partially treated oruntreated wastewater is released into a body of water, such as a river,in order not to exceed the amount of wastewater the plant was designedto handle.

As noted above, discharge of this untreated wastewater into bodies ofwater will endanger and kill resident plant and aquatic life in thewater. Untreated wastewater also contains a number of disease pathogensthat are extremely harmful to humans. For example, untreated wastewateris one of the leading causes of dysentery, which can be lifethreatening. Thus, if a significant amount of untreated wastewater isdischarged into a body of water, that body of water will becomeunavailable for human consumption. On the other hand, if the treatmentplant processes the larger-than-normal amounts of untreated wastewater,instead of diverting a portion into a body of water, the influx ofuntreated wastewater would wash away the bacteria populations or biomassused by the plant to treat the untreated wastewater, which would disruptthe entire biological treatment process of the plant. Further, as notedabove, wastewater treatment is particularly needed in developingnations, and such large-scale treatment plants may not be available.

In rural areas and in developing nations, construction of centralizedwastewater treatment plants may be too expensive to build and maintain.In addition, the cost of connecting residences and businesses in ruralareas to a centralized treatment plant via sewage lines may beimpracticable due to the greater distance between the those residencesand businesses. In such areas, septic systems are usually utilized totreat wastewater. A septic tank is typically a large tank locatedunderground on an owner's property. Septic tanks are categorized ascontinuous flow systems because wastewater flows into the septic tank atone end, and the same amount of wastewater that entered will exit thetank at the other end. The purpose of a septic tank is to provide aminimal amount of anaerobic treatment and to retain any solids in thewastewater to allow only the liquid wastewater effluent to pass throughto prevent drain field disposal lines from becoming clogged. However,since the wastewater leaving the septic tank has only been minimallytreated, the wastewater will be a detriment to the environment due toits organic and nutrient contaminants, as noted above, and may not berecovered as reclaimed water. Furthermore, as solids build up inside theseptic tank, a phenomenon known as periodic upset may occur, causingsolids to flow out of the septic tank and into the field lines connectedto the tank. Eventually, these field lines will clog due to the buildupand carryover of solids. When this occurs, the field lines have to becleaned or replaced, if possible, which means destruction to a portionof the owner's property as well as increased expense to the owner. Amore extreme condition would be the failure of the drain field withoutan adequate replacement area on the property.

Further, it has been found that certain soils are only capable ofreceiving and dispersing a limited amount of wastewater, given theparticular soil structure, geology, and groundwater conditions. In thisinstance, practice has shown that a highly treated wastewater can bedischarged to drainfields possessing limited hydraulic and/or soiltreatment capacity. Furthermore, a high quality effluent can bereclaimed and used for secondary purposes, such as irrigation,industrial rinse and cooling, and grey water uses, for example.

Centralized wastewater treatment systems that treat over 1,500 gallonsper day typically utilize either concrete, steel or fiberglass tanks tohouse the systems. These materials have been utilized for decades, dueto the unavailability of other options. Concrete and steel, due to theirparticular material properties, are highly subject to corrosion and arenot suited to withstand the corrosive gases and fluctuations in pHcommon in wastewater and wastewater treatment.

Further, both concrete and steel tanks are difficult and expensive tofabricate, transport and install. The average life expectancy of aconcrete or steel wastewater tank is only between twenty and thirtyyears. Furthermore, to date, the only tank material option for largewastewater treatment systems over 100,000 gallons per day is concrete.Fiberglass, although a more tolerant material with a longer lifeexpectancy, is limited in its detailing capabilities and delaminateswhen subjected to a sharp pressure point or conditions of constantfriction.

Fiberglass tanks are typically constructed utilizing pre-developed moldsand are relatively inflexible in adjustment to specific projectrequirements. This inflexibility results in additional required tankage,yard piping and mechanical equipment, thus resulting in increasedmaintenance and operational issues and expenses.

Additionally, steel, concrete and fiberglass tanks are all relativelydifficult to repair when damaged. An additional option for wastewatertreatment systems under 1,500 gallons per day is the utilization ofrotationally or injection molded plastic tankage as the housing. Suchtanks are commonly used for septic tanks, grease traps and smalltreatment systems, however, the overall majority of these tanks areprone to crushing when emptied and are limited in size due to thepre-developed molds. It would be desirable to form such tankage from amaterial that would alleviate these problems.

Thus, a wastewater treatment system and method solving theaforementioned problems is desired.

SUMMARY OF THE INVENTION

The wastewater treatment system is a portable, pre-assembled system thatcollects and treats wastewater. The system includes either small,vertically disposed tankage or larger, horizontally disposed cylindricaltankage connected to an inlet and outlet pipe. Preferably, the tankage,or housings, is formed from steel-reinforced plastic. The horizontalconfiguration systems are expandable in the field by butt-welding tanksend-to-end, preferably utilizing known thermoplastic fuse weldingtechniques.

The wastewater treatment system provides multiple techniques fordecontaminating wastewater contained within a single system, thusoptimizing the decontamination of the wastewater. The system may besized to serve a single home, a cluster of homes and businesses, amunicipality, or single or multiple industrial or agriculturalfacilities. The wastewater treatment system includes a tank, which ispreferably cylindrical and may be manufactured from steel-reinforcedplastic or the like, having at least one chamber defined therein. Thesystem includes the tank, which defines at least one internal chambertherein, the tank preferably being formed from steel-reinforced plastic.An inlet port forms a conduit for inlet of wastewater into the at leastone chamber, and an outlet port forms a conduit for discharge of treatedwastewater from the tank. Preferably, the at least one chamber defines agravity clarifier chamber for precipitating solid waste from thewastewater for collection thereof.

In one embodiment, the housing includes first and second partition wallsdividing the tank into first, second and third chambers. The firstchamber includes at least one first effluent filter and further containsanaerobic bacteria for removal of organic waste and nutrients, such asnitrogen, from the wastewater received therein. The first chamber isconfigured for at least partial removal of particulate and organicmatter from the wastewater.

An inlet port forming a conduit for inlet of the wastewater into thefirst chamber is provided through an outer housing of the system.Similarly, an outlet port forming a conduit for discharge of treatedwastewater from the third chamber is further provided. A first port isformed through the first partition wall for selective transfer of thewastewater from the first chamber to the second chamber. The secondchamber includes an air diffuser and further contains aerobic bacteriafor further removal of organic waste material from the wastewaterreceived therein. A stationary fixed film or floating media assembly isprovided for fostering growth of the aerobic bacteria within the secondchamber. The microorganisms contained within the second chamber arecommonly referred to as “activated sludge” or “biomass”, and are morespecifically referred to as “suspended growth” and “attached growth”bacteria.

A second port is formed through the first partition wall for selectivetransfer of the wastewater from the second chamber to the third chamber.The third chamber includes a return activated sludge pump assembly andat least one second effluent filter. A third port is formed through thesecond partition wall for selective transfer of settled waste solidsfrom the third chamber to the first chamber. Resultant purified water isselectively discharged from the outlet port, after passing through thesecond effluent filter. Preferably, the tank is equipped with a bottomplate, which serves as an antifloatation collar, thereby preventinginadvertent floatation of an empty tank that may occur during or afterconstruction.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic top view of a wastewater treatment systemaccording to the present invention, shown with the upper cover removed.

FIG. 2 is a partial, diagrammatic section view of the wastewatertreatment system, taken along lines 2-2 of FIG. 1.

FIG. 3 is a partial, diagrammatic section view of the wastewatertreatment system, taken along lines 3-3 of FIG. 1.

FIG. 4 is a partial, diagrammatic section view of the wastewatertreatment system, taken along lines 4-4 of FIG. 1.

FIG. 5 is a top view of the wastewater treatment system according to thepresent invention.

FIG. 6 is a diagrammatic top view of an alternative embodiment of awastewater treatment system according to the present invention, shownwith the upper cover removed.

FIG. 7 is a partial, diagrammatic section view of the wastewatertreatment system of FIG. 6, taken along view lines 7-7 of FIG. 6.

FIG. 8 is a partial, diagrammatic sectional view of the wastewatertreatment system of FIG. 6, taken along lines 8-8 of FIG. 6.

FIG. 9 is a partial, diagrammatic section view of the wastewatertreatment system, taken along view lines 9-9 of FIG. 6.

FIG. 10 is a diagrammatic side view of another alternative embodiment ofa wastewater treatment system according to the present invention.

FIG. 11 is a diagrammatic side view of another alternative embodiment ofa wastewater treatment system according to the present invention.

FIG. 12 is a diagrammatic side view of yet another alternativeembodiment of a wastewater treatment system according to the presentinvention.

FIG. 13 is a diagrammatic side view of still another alternativeembodiment of a wastewater treatment system according to the presentinvention.

FIG. 14 is a diagrammatic side view of another alternative embodiment ofa wastewater treatment system according to the present invention.

FIG. 15 is a partial side view of a housing for a wastewater treatmentsystem according to the present invention.

FIG. 16 is a partial side view in section of the housing of FIG. 15.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-4, in a first embodiment, the wastewater treatmentsystem 10 is preferably formed as a single enclosed unit containedwithin a housing 12. The housing 12 is substantially cylindrical, and ispreferably formed from steel-reinforced plastic or the like. As will bedescribed in detail below, the system 10 provides three separatetechniques for decontaminating wastewater contained within the singlesystem, thus optimizing the decontamination of the wastewater.

The wastewater treatment system 10 includes the housing 12 forming anouter tank, and first and second partition walls 18, 50, respectively,dividing the tank into first, second and third chambers 16, 22, 28,respectively. The first partition wall 18 generally bisects thecylindrical housing 12 diametrically, and the second partition wall 50is orthogonal to the first partition wall 18, extending radially andgenerally bisecting one of the two semicylindrical spaces formed by thefirst partition wall 18. The first chamber 16 preferably houses ananoxic environment and includes at least one first effluent filter 20,and further contains anaerobic and facultative bacteria for the removalof organic waste material and nitrogen from the wastewater receivedtherein. The first chamber 16 is configured for at least partial removalof particulate and organic matter from the wastewater. The housing 12may be formed from steel-reinforced plastic or any other suitablematerial.

An inlet port 14 (with a downpipe assembly) forming a conduit for inletof the wastewater into the first chamber 16 extends through the outerhousing 12 of the system 10. Similarly, an outlet port 52 forming aconduit for discharge of treated wastewater from the third chamber 28 isfurther provided. Untreated, raw wastewater enters the first chamber 16through the inlet port 14 from residential or small commercialfacilities. For example, the system 10 may receive approximately 1,500gallons per day from a residential or small commercial producer ofwastewater. High-quality, purified effluent is discharged through theoutlet port 52 to be received by an alternative subsurface drainfield(such as a gravel trench or drip irrigation system), or may be directlydischarged into a stream or other body of water, or may further bere-used for spray irrigation or the like.

The overall configuration, including the dimensions and configuration ofthe system 10, may vary. An exemplary system 10 capable of processing500 gallons of wastewater per day may have a substantially cylindricalouter housing 12 having a diameter of approximately six feet and aheight of approximately six feet. An exemplary system of similarconfiguration but capable of processing 750 gallons per day may have adiameter of approximately seven feet and a height of approximately sixfeet. Similarly, a system 10 capable of processing 1,000 gallons per daymay have a diameter of approximately eight feet and a height of sixfeet, and a system 10 capable of processing 1,500 gallons per day mayhave a diameter of approximately ten feet and a height of six feet.Preferably, the housing 12 is configured for burial within the ground.

When wastewater is received within the first, anoxic chamber 16,untreatable materials that are indigestible to the anaerobic bacteriacontained therein are filtered by the effluent filter 20, preventingtheir transfer to the second, bioreactor chamber 22. The first chamber16 provides the first stage of wastewater treatment and organicdigestion, and may be complemented by recycled wastewater fromadditional downstream tanks. Preferably, the anoxic chamber 16 has avery low dissolved oxygen content of approximately 0.5 mg/L or less,thus fostering microbial metabolism typically associated with nitrogenremoval from a wastewater stream (i.e., anaerobic or facultativebacteria). Any suitable strain of anaerobic bacteria known for digestingorganic materials in wastewater may be utilized, as is well known in thefield of wastewater treatment. Similarly, any suitable type of effluentfilter may be utilized. The effluent filter 20 is preferably removable,allowing for easy replacement or repair thereof.

Preferably, the bacteria in the system 10 are naturally occurringspecies of microorganisms, which are typically already found inabundance in wastewater streams. It should be noted that the system 10primarily uses bacteria known for nutrient removal in the digestion andremoval of the organic and nutrient wastewater components.Microorganisms that may be used for this purpose include nitrobacter andnitrosomas, as well as other similar, numerous species possessingsimilar biologic and metabolic characteristics. These and similarmicroorganisms are facultative, and change their metabolism dependingupon the amount of dissolved oxygen present in the wastewater treatmentplant. By recycling from an anaerobic zone to an aerobic zone and thenback to the anaerobic zone, as will be described below, thesefacultative microorganisms eventually metabolize nitrogen compounds sothat gaseous nitrogen is released into the atmosphere.

A first port is formed through the first partition wall 18 for selectivetransfer of the partially treated wastewater from the first chamber 16to the second chamber 22. As best shown in FIGS. 2 and 3, treatedwastewater passes through an inlet pipe 46 (with a downpipe assembly)into the main body of the second chamber 22. Preferably, the partiallytreated wastewater flows under the force of gravity from the firstchamber 16 to the second chamber 22, with no additional pumpingrequired. Any suitable type of valving may be utilized to regulate andcontrol the flow of the wastewater through the first port and inlet pipe46.

The second chamber 22 includes an air diffuser 26, and further containsaerobic bacteria for further removal of organic waste material from thewastewater received therein. A fixed film assembly 30 is provided forreceiving and fostering growth of the aerobic bacteria within the secondchamber 22. A blower assembly 24, a linear air pump, or any othersuitable source of compressed or pressurized air is provided fordelivering air through the air diffuser 26 via conduit 32 (best shown inFIG. 3). The air diffuser 26 may be a membrane air diffuser producing astream of fine air bubbles, a coarse air diffuser or any other suitabletype of air diffuser for aerating and mixing the partially treatedwastewater contained in the second chamber 22. Preferably, the blower 24includes a pressure release valve, allowing for user-controllable airflow adjustment and waste air release. The blower assembly 24, or anyother suitable source of pressurized air, may be located in any suitablelocation, and may provide air to the diffuser 26 through any suitabletype of piping or the like. The air pump and diffuser assembly provideprimary aeration so that the dissolved oxygen content in the secondchamber 22 is a minimum of approximately 2.0 mg/L. The air pump furtherprovides actuation of the scum removal system 34 and return activatedsludge pumping system 42, as shown in FIG. 4.

The fixed film assembly 30 may be perforated plastic tubing, a pluralityof floating individual plastic media objects, or the like, which serveas a surface for the aerobic bacteria to grow and bond onto. Anysuitable type of aerobic bacteria used in the removal of organic wastesmay be utilized. A second port is formed through the first partitionwall 18 for selective transfer of the wastewater from the second chamber22 to the third, or clarifying, chamber 28. Preferably, the partiallytreated wastewater (commonly referred to as a “mixed liquor”) flows fromthe second, bioreactor chamber 22 into the stilling well 55 formedbehind baffle wall 58, and then into the third, clarifying chamber 28under the force of gravity, through pipe 36 with downpipe assemblies atport 54, with no additional pumping being required.

Preferably, the fixed film assembly 30 is permanently attached to theinterior of the second chamber 22. As noted above, any suitable type ofair diffuser 26 may be utilized, such as a membrane air diffuser or acoarse air diffuser. It should be understood that the orientation of theair diffuser 26, shown in FIG. 3, is shown for exemplary purposes only.The air diffuser 26 may have any suitable orientation, and is preferablyremovable, allowing for repair or replacement thereof.

The return activated sludge pumping system 42 in the third chamber 28utilizes a siphon-ejection air lift assembly, which pumps thegravity-settled suspended solids from the mixed liquor at a selectablepre-determined rate of approximately four times the system flow backinto the first anoxic chamber 16 through a conduit. A third port 51,formed through the second partition wall 50, allows for the selectivetransfer of the suspended waste solids from the third chamber 28 to thefirst chamber 16. Preferably, a second surface scum removal system 34,utilizing another siphon-ejection air lift assembly, is provided forcollecting scum from the clarifier surface and pumping this materialback to the stilling well 62 at a rate of approximately one-tenth of thesystem design flow. A pipe wasting air from the blower assembly may beprovided to direct excess air to the clarifier surface, so that air flowforces floating scum and solids toward the scum removal pump system 34.The return activated sludge pump assembly 42 and the scum removal pumpassembly 34 may be regulated by any suitable type of valving, such as anair needle valve block assembly. The needle valves control the flow ofpressurized air through a flexible hose or rigid conduit to eachsiphon-ejection air lift assembly.

The floating scum in chamber 28 is received and collected via inlet pipe75, and the waste exits into the stilling well 55 behind the baffle wall58 at port 60, via a siphon-ejection pump 76 mounted below, andconnected to, forcemain 40. The return activated sludge is returned backinto the first chamber 16 via a return activated sludge siphon-ejectionpump 38, which is mounted below the return activated sludge forcemain44.

As shown in FIGS. 1 and 4, an additional stilling well assembly 56 isprovided, the assembly 56 being mounted within the third chamber 28.Resultant purified wastewater is selectively discharged from the outletport 52. Preferably, a removable effluent filter is provided forcovering the outlet port 52, thus providing tertiary effluent filtrationto remove any remaining clarifier floc and/or fine suspended solidsprior to the effluent discharge.

The effluent filter may be formed frompolyester/polyethylene/polystyrene fiber, or from a flexible foammaterial or the like, contained within or exterior to a perforatedcanister or the like connected to outlet port 52. The removable effluentfilter may be contained within a separate filter sleeve assembly havinga vertical, perforated plastic tube that is affixed to the clarifierfloor. The effluent filter, as described above, may be any suitable typeof effluent filter, and is preferably removable for easy repair orreplacement thereof. Additionally, a packaged membrane effluent filterassembly may be utilized in lieu of the removable effluent filter andfilter sleeve assembly.

Preferably, a relatively simple electronic control assembly is providedfor user control and programming. The controls allow for the selectiveoperation and control of the blower assembly 24, along with a timer forprogrammable actuation of aeration within the second chamber 22, thusallowing for energy savings and further promoting the inherent nitrogenremoval biological process. A sensor and coupled alarm may further beprovided for monitoring operation of the blower 24. An alarm signal isdelivered to the user in the event of power or blower failure.

As shown in FIG. 5, the upper cover 66 of the tank 12 preferablyincludes at least two hatches, the access hatch 68 being pivotallysecured by hinges 74, allowing selective access to the secondbio-reactor chamber 22 for repair or replacement of the air diffuserand/or film assembly. Similarly, an access hatch 70 is provided(pivotally joined to cover 66 by hinges 72) for accessing the interiorsof the first chamber 16 and the third chamber 28. It should beunderstood that the access hatches are shown for exemplary purposesonly, and that any suitable type, or number, of hatches may be utilized.

For example, in the embodiment of FIGS. 6, 7, 8 and 9, three suchhatches (one for each chamber) 168, 169 and 170 are provided. Each hatch168, 169, and 170 is configured as a manhole-type cover, rather than thehinged rectangular covers shown in FIG. 5. With such a configuration,the manhole-type hatches are preferably formed on risers, allowing atleast six inches of clearance. Thus, when the housing 12 is buried inthe ground, the hatches are easily accessible at ground level. A vent 48may be incorporated into one of these risers, as a further alternative.

Returning to the embodiment of FIGS. 1-5, the outer tank or housing 12may be formed from any suitable material, preferably a steel-reinforcedplastic or the like, allowing for a suitably strong housing 12 capableof withstanding an exterior earth load (when the system 10 is buried inthe ground), and which is resistant to corrosion and biologicaldegradation. Contech Construction Products, Inc.® of West Chester, Ohiomanufactures a steel-reinforced polyethylene (SRPE) material possessinga steel exterior spiral-ribbed banding that is encapsulated with ahigh-density polyethylene plastic, sold under the name DuroMaxx™. Such amaterial, or similar materials, may be used in the manufacture of thehousing 12 to provide increased earth and dynamic load support. Itshould be understood that the DuroMaxx™ housing is the preferred housingfor all embodiments of the wastewater treatment system described herein.

Referring to the alternative embodiment of FIGS. 6-9, the wastewatertreatment system 100 includes the housing 112 forming an outer tank, andfirst and second partition walls 118, 150, respectively, dividing thetank into first, second and third chambers 116, 122, 128, respectively.The first chamber 116 preferably houses an anoxic environment andincludes at least one first effluent filter 120, and further containsanaerobic and facultative bacteria for the removal of organic wastematerial and nitrogen from the wastewater received therein. The firstchamber 116 is configured for at least partial removal of particulateand organic matter from the wastewater.

An inlet port 114 (with a downpipe assembly) forming a conduit for inletof the wastewater into the first chamber 116 extends through the outerhousing 112 of system 100. The inlet port 114 may be a 4-inch diameterPVC pipe or the like. Similarly, an outlet port 152 forming a conduitfor discharge of treated wastewater from the third chamber 128 isfurther provided. Untreated, raw wastewater enters the first chamber 116through the inlet port 114 from residential or small commercialfacilities. For example, the system 100 may receive approximately 1,500gallons per day from a residential or small commercial producer ofwastewater. High-quality, purified effluent is discharged through theoutlet port 152 to be received by an alternative subsurface drainfield(such as a gravel trench or drip irrigation system), or may be directlydischarged into a stream or other body of water, or may further be usedfor spray irrigation or the like. Preferably, the housing 112 isconfigured for burial within the ground.

When wastewater is received within the first, anoxic chamber 116,untreatable materials that are indigestible to the anaerobic bacteriacontained therein are filtered by the effluent filter 120, preventingtheir transfer to the second, bioreactor chamber 122. The first chamber116 provides the first stage of wastewater treatment and organicdigestion, and may be complemented by recycled wastewater fromadditional downstream tanks. Preferably, the anoxic chamber 116 has avery low dissolved oxygen content of approximately 0.5 mg/L or less,thus fostering microbial metabolism typically associated with nitrogenremoval from a wastewater stream (i.e., anaerobic bacteria). Anysuitable strain of anaerobic bacteria known for digesting organicmaterials in wastewater may be utilized, as is well known in the fieldof water treatment. Similarly, any suitable type of effluent filter maybe utilized. The effluent filter 120 is preferably removable, allowingfor easy replacement or repair thereof.

A first port 146 is formed through the first partition wall 118 forselective transfer of the partially treated wastewater from the firstchamber 116 to the second chamber 122. As best shown in FIGS. 7 and 8,treated wastewater passes through the inlet 146 (with downpipeassemblies) into the main body of the second chamber 128. Preferably,the partially treated wastewater flows under the force of gravity fromthe first chamber 116 to the second chamber 122, with no additionalpumping required. Any suitable type of valving may be utilized toregulate and control the flow of the wastewater through the inlet 146.

The second chamber 122 includes an air diffuser 126, and furthercontains aerobic bacteria for further removal of organic waste materialfrom the wastewater received therein. A fixed film assembly 130 isprovided for receiving and fostering growth of the aerobic bacteriawithin the second chamber 122. A blower assembly 124, a linear air pump,or any other suitable source of compressed or pressurized air isprovided for delivering air through the air diffuser 126 via a conduit132 (best shown in FIG. 8). The air diffuser 126 may be a membrane airdiffuser, a coarse air diffuser or any other suitable type of airdiffuser for aerating and mixing the partially treated wastewatercontained in the second chamber 122. Preferably, the blower 124 includesa pressure release valve, allowing for user-controllable air flowadjustment and waste air release. The blower assembly 124, or any othersuitable source of pressurized air, may be located in any suitablelocation, and may provide air to the diffuser 126 through any suitabletype of piping or the like. As in the previous embodiment, the air pumpand diffuser assembly provide primary aeration so that the dissolvedoxygen content in the chamber 122 has a minimum of approximately 2.0mg/L. The air pump further provides actuation of the scum removal system134 and the return-activated sludge pumping system 142.

A second port is formed through the first partition wall 118 forselective transfer of the wastewater from the second chamber 122 to thethird or clarifying chamber 128. Preferably, the partially treatedwastewater flows from the second, bioreactor chamber 122 into thestilling well 155 behind baffle wall 158, through baffle opening 159,and then into the third, clarifying chamber 128 under the force ofgravity, with no additional pumping being required.

The return activated sludge pumping system 142 of the third chamber 128utilizes a siphon-ejection air lift assembly, which pumps thegravity-settled suspended solids from the mixed liquor at a selectablepre-determined rate of approximately four times the system design flowback into the first anoxic chamber 116 through the conduit 148 (shown inFIG. 6). The third port 148, formed through the second partition wall150, allows for the selective transfer of the suspended waste solidsfrom the third chamber 128 to the first chamber 116. Preferably, asecond surface scum removal system 134, utilizing anothersiphon-ejection air lift assembly, is provided for collecting scum fromthe clarifier surface and pumping this material back to the stillingwell 155 at a rate of approximately one-tenth of the system design flow.A pipe wasting air from the blower assembly may be provided to directexcess air to the clarifier surface, so that air flow forces floatingscum and solids toward the scum removal system 134. The return activatedsludge pump assembly 142 and the scum removal pump assembly 134 may beregulated by any suitable type of valving, such as an air needle valve.

The floating scum in chamber 128 is received and collected via an inletpipe 175, with the waste exiting into the stilling well 155 behind thebaffle wall 158 at port 160, via a siphon-ejection pump 176, mountedbelow, and connected to, forcemain 140. The return-activated sludge isreturned back into the first chamber 116 via a return activated sludgesiphon-ejection pump 138 mounted below the return activated sludgeforcemain 144. FIG. 6 further shows a pair of routed flexible air lines103, 105, which preferably lead to a needle valve block 107, which isalso in communication with a conduit 132 for air flow rate adjustment.

FIGS. 6 and 8 best illustrate the stilling well 155 behind the bafflewall 158 formed between wall 118 and the second chamber 122 (as bestshown in FIG. 8, a stilling well inlet opening 159 is formed through thebaffle wall 158). As shown in FIG. 6, an inspection and maintenance port162 is preferably formed through the cover of the housing 112 above thestilling well chamber. Resultant purified water is selectivelydischarged from the outlet port 152. Preferably, a removable effluentfilter 151 is provided in a filter sleeve 153 in the path of the outlet152, thus providing tertiary effluent filtration to remove any remainingclarifier floc and/or fine, suspended solids prior to the effluentdischarge. The effluent filter 151 may be formed frompolyester/polyethylene/polystyrene fiber or strand foam material or thelike contained within a perforated canister or the like connected to theoutlet port 152. As will be described below, the system may includeadditional treatment, such as an in-line ultraviolet disinfectionsystem. Further, preferably, due to the corrosive nature of thematerials contained within the tank, all internal piping and associatedsupports are formed from plastic or similarly non-corrosive materials,with no corrosive metal fasteners or the like. The bottom plate 177,which is preferably formed from plastic or a combination of steel andplastic or the like, provides buoyancy flotation resistance.

In the alternative embodiments of FIGS. 10 and 11, the system 200utilizes a steel-reinforced plastic tank 212 placed in a horizontalposition. This configuration permits construction of the treatmentsystem 200 in larger sizes, varying from 2,000 gallons per day andlarger. Horizontal tank construction can utilize steel-reinforcedplastic tanks 212 having diameters of sixty inches, seventy-two inches,eighty-four inches, ninety-six inches, one hundred and eight, onehundred twenty inches, one hundred and forty four inches and larger. Thehorizontally placed tank 212 permits fabrication of larger wastewatertreatment systems 200 having multiple treatment compartments, including,but not limited to, a flow equalization and influent pumping compartment202, an anoxic compartment 204, a bioreactor compartment 206, aclarification compartment 208 (for effluent filtration), and a sludgedigestion compartment 210.

It should be understood that in addition to the various forms oftreatment described below, the system 200 may further incorporateadditional conventional methods of treatment, such as, but not limitedto, activated sludge/extended aeration (AS/EA), integrated fixed filmactivated sludge (IFAS), moving bed biological reactors (MBBRs),sequencing batch reactors (SBRs), membrane bioreactors (MBRs), tricklingfilters (TFs), biofilters (BFs/BAFs), or the like. Further, it should beunderstood that the housing may include additional compartments, whichmay include, but are not limited to, a chlorine contact chamber, a fat,oil and grease (FOG) separator chamber, a trickling filter chamber, apost-aeration chamber, an effluent pump station chamber and aUV-disinfection chamber.

It should be further understood that the compartments within the tankmay be repurposed to facilitate other methods of treatment. For example,the anoxic compartment may be converted to an anaerobic digester throughthe implementation of mixers and heating exchangers. Anaerobic digestionis widely used as a renewable energy source because the process producesa methane-rich biogas suitable for energy production, thus helping toreplace fossil fuels. The nutrient-rich digestate that is produced inthe process can be used as fertilizer.

Using the exemplary figures given above, the 72-inch diameter horizontalsteel-reinforced plastic tank 212 with an approximate overall length ofthirty feet would have a treatment capacity of approximately 5,000gallons per day. A 120-inch diameter horizontal steel-reinforced plastictank 212 with a length of approximately forty feet would have atreatment capacity of approximately 20,000 gallons per day.

In the system 200 of FIGS. 10 and 11, wastewater enters the firstcompartment 202 through an inlet port 214, which, using the exemplaryfigures given above, may have a size range between approximately fourinches and eight inches. Influent is stored temporarily therein toequalize daily flows in order to match the treatment system's averagedaily treatment flow. Wastewater is pumped through either a simplex orduplex pumping system utilizing a pump 216, which may be either an airlift or electric submersible pump(s), to pass to the anoxic compartment204. Control of the pumping system is either continuous or intermittent,depending upon the type of pump and its control features. Submersiblepressure transducers 218 may also be utilized to monitor and controlelectric pump operation. Additionally, it should be noted thatcompressed air from a blower assembly 222 is preferably deliveredthrough air piping 224 to a submerged air diffuser 227 to keep unsettledsolids in suspension.

After pumping from the basin of the flow equalization compartment 202,the wastewater is mixed in the anoxic compartment 204, where facultativebacteria utilize incoming carbon food sources in the wastewater stream,along with oxygen contained either in the form of dissolved oxygen orchemically bound in available nitrates, along with further nitrites tofoster bacterial digestion of the incoming wastewater contaminants andnutrients. Additional recycling and mixing in the anoxic compartment 204takes place in the form of mixed liquor suspended solids (MLSS) pumpingfrom the bioreactor compartment 206 through the use of an MLSS pumpingsystem 220.

Wastewater in the anoxic compartment 204 flows by gravity into thebioreactor compartment 206, where additional wastewater treatment isprovided in the form of aeration. Aeration is provided by an electriccompressed air blower assembly 222. The blower assembly 222 may beeither a regenerative air blower or a positive displacement air pump.Compressed air from the blower assembly 222 is delivered through airpiping 224 to a series of submerged air diffusers 226. The air diffusers226 disperse air in the form of air bubbles, which rise to the watersurface. The diffusers 226 can be either coarse air or fine air units,depending upon the level of required wastewater treatment.

Aeration from the blower assembly 222 transfers atmospheric oxygen intothe wastewater. Aeration from the blower assembly 222 further providesmixing of the wastewater, fostering growth of the activated sludge. Asin the previous embodiments, the use of a fixed film component, eitherin the form of a stationary plastic assembly or free-floating plasticmedia, fosters the formation of the attached growth microorganisms. Thecombined fixed film and activated sludge process promotes advancednitrification and de-nitrification of the wastewater, and ultimately theremoval of nitrogen contaminants.

The MLSS pumping assembly 220 may utilize either an air-lift pump orsubmerged electric pumps, and may have one or more pumps implementedsimultaneously. The MLSS pump assembly 220 preferably pumps mixed liquorto the anoxic compartment 206 at a rate of approximately four times thetreatment system design flow, although this rate can be variable andadjusted to meet treatment system requirements. After treatment in thebioreactor compartment 206, wastewater flows by gravity through astilling well assembly 228, shown in FIG. 11.

In the embodiment of FIG. 11, the stilling well assembly 228 reduces, bygravity, the amount of mixed liquor suspended solids that will dischargefrom the bioreactor compartment 206. Wastewater then enters theclarification compartment 208, by way of a plastic down pipe assembly240, where the mixed liquor suspended solids will settle, by gravity, tothe bottom of a sloped sump assembly 230. The sloped sump assembly 230is preferably formed using plastic sheet materials that create atetrahedral assembly that directs settled solids to the bottom of theclarifier chamber 208. The void space between the sloped sump assembly230 and the housing 212 is preferably filled completely with a closedcell urethane foam 231 or the like.

A return activated sludge pump assembly 232 then pumps the settledsolids or biomass back to the bioreactor compartment 206 for additionaltreatment. After settling of the solids, the clarified wastewater oreffluent gravity flows up and through an effluent discharge weir 234.The discharge weir 234 is preferably fabricated from plastic and has anadjustable saw tooth weir gate that can be calibrated to permitconsistent effluent discharge from the clarifier compartment 208.Additionally, the clarifier compartment 208 is equipped with a surfacescum removal assembly 236 that will remove floating scum and solids fromthe clarifier water surface. The scum removal assembly 236 includes aplastic scum intake port 238 connected by plastic piping to an air-liftpump. The scum removal assembly pumps the scum back to the bioreactorcompartment 206 for additional treatment.

In the embodiment of FIG. 10, a membrane filter assembly 242 (or,alternatively, an effluent filter) replaces the clarifier. The membraneassembly 242 includes a manufactured membrane filter unit 244, which mayutilize an elastomeric, polymeric, or ceramic membrane filter media. Themembrane unit 244 is modular and can be installed in variousconfigurations of the system 200.

The membrane unit 244 utilizes compressed air from either the bioreactorblower 222 or a dedicated membrane blower assembly 246. Compressed airfrom the membrane blower 246 provides additional aeration of the mixedliquor and further complements nitrification and de-nitrification. Themembrane filter assembly 242 discharges effluent or permeate through apermeate discharge pipe 248, that can be discharged to the localenvironment or reused as reclaimed or recycled wastewater.

Control of wastewater levels in the membrane compartment 208 isimplemented through the use of pressure transducer or mercury floatswitch assemblies connected to a master wastewater treatment plantelectric control panel. A recirculation or membrane tank pump 250 isprovided in the bioreactor compartment 206. The recirculation pump 250maintains water levels for proper membrane unit operation. Therecirculation pump 250 may be configured so that its piping 252 can pumpmixed liquor to the membrane compartment 208 or the sludge digestercompartment 210.

The sludge digester compartment is provided for the treatment of wastemixed liquor suspended solids or waste sludge. This compartment containsa diffuser or series of diffusers 254 that provide aeration and mixingof the waste sludge. A sludge dewatering pump or supernatant pumpassembly 229 may be provided so that supernatant water can be pumpedfrom the sludge digester compartment 210 back to the bioreactorcompartment 206. The pump assembly 229 is similar to pump assembly 216and may hang from the upper wall by a chain (as shown) or may besimilarly supported in any suitable manner. Accumulated waste sludge inthe sludge digester compartment 210 will be pumped and dischargedoff-site by approved methods, as is typical of the wastewater treatmentprocess. Preferably, due to the corrosive nature of the materialscontained within the tank, all internal piping is formed from plastic orsimilar non-corrosive materials, with no corrosive metal fasteners orthe like. It should be noted that FIG. 10 illustrates an outer housing290 adapted for partial burial applications, where the pumps andcontrols are secured to the bulkhead in a plastic/corrosion-resistantmetal enclosure. It should be understood that the pumps and controlsmay, alternatively, be positioned outside of the tank, against thebulkhead, rather than being positioned within the tank.

Access to the horizontal tank wastewater treatment system 200 isprovided through either circular access hatches 256, including risers(preferably formed from plastic) and removable lids (preferably formedfrom plastic), or through a rectangular access hatch 291 (preferablyformed from corrosion-resistant metal), as described in the previousembodiments. Similarly, as in the previous embodiments, control of thehorizontal tank wastewater treatment system 200 is accomplished throughthe use of an electronic control panel. The control panel will controlinfluent pumping, bioreactor aeration, MLSS pumping, return activatedsludge pumping, membrane aeration, recirculation pumping, sludgedigester aeration, supernatant pumping, etc. The control panelpreferably includes both manual and automatic switches, indicatorlights, audible warning horns, visible warning lights, and an optionalauto-dialer mechanism that can notify a manned station in the event of awastewater treatment mechanical problem or report other metered datarequired of the particular system.

In the above embodiments, as noted previously, the size of the tanks, aswell as the materials used in their construction, may be varied asneeded. Systems capable of treating up to two million gallons ofwastewater per day (or more) are envisioned. The tanks themselves couldbe manufactured off-site in manufacturing plants or on-site. At aparticular work site, the steel-reinforced plastic material, or thelike, which forms the tank housing, could be unspooled from spools witha mobile winder that turns the material in a manner similar to that of acorkscrew, constructing pipes (via welding) as it turns.

The pipes could then be manufactured into treatment tank units on-site,utilizing manufacturing equipment. Furthermore, the units could be buttwelded, end-to-end, in the field by way of thermoplastic fuse weldingtechniques, or through other methods, in order to facilitate largetreatment capacities.

FIG. 12 illustrates a further alternative system 300 adapted for severeduty conditions. The system 300 includes an inner tank 312, similar tothe tank 212 described above with reference to FIG. 10, mounted withinan outer housing 400, which is similar to a conventional cargo orshipping container. The floor 406 of the inner tank 312 may be separatedfrom the floor of the outer housing 400 by layers of insulation 402 orthe like. The remaining space between the exterior of the inner tank 312and the outer housing 400 may be filled with insulation 404, such asclosed cell urethane foam. The system 300 is adapted for wastewatertreatment operations in remote and harsh or difficult locations, such asmining camps, temporary work camps, seasonal villages and resorts,temporary or semi-temporary military bases and installations, militaryForward Operating Bases (FOBs), arctic or sever cold weather operations,desert or high temperature climates, or other facilities requiring adurable, reliable and sustainable packaged wastewater treatmentfacility. The outer housing 400 allows the system 300 to be easilytransported with minimal setup of the system. The outer housing 400further allows the system 300 to be at least partially buried. A door412 may be provided in the outer housing 400, allowing user access tothe compartment 310. A ladder 414 may be mounted opposite the door 412,allowing easy user access to the roof of the housing 400.

The outer housing 400 may be a conventional steel shipping container orthe like. Such containers may have dimensions of approximately eightfeet in width, approximately 8½ feet in height and 40 feet in length,for example. The insulation 404 preferably has an R-insulation value ofapproximately six per one inch of foam insulation. The composite Rinsulation value for the entire system 300 is preferably approximately70. The system 300 preferably has a treatment capacity of approximately15,000 gallons per day, although it should be understood that thisdepends upon the strength of the influent and required effluentperformance. The use of membrane filtration, as described above, mayincrease total treatment system capacity to approximately 20,000 gallonsper day.

As in the previous embodiment, the system 300 utilizes asteel-reinforced plastic tank 312 placed in a horizontal position. Thehorizontally placed tank 312 permits fabrication of larger wastewatertreatment systems 300 having multiple treatment compartments, including,but not limited to, a flow equalization and influent pumping compartment302 (i.e. the pre-anoxic zone), an anoxic compartment 304, a bioreactorcompartment 306, and a clarification compartment 308 (for effluentfiltration). The bulkhead walls of the tank may be formed from solidsheets of high density polyethylene (HDPE) or the like, having athickness between one and three inches, for example. Additional HDPEstiffeners may be welded to an external surface thereof (verticallyand/or horizontally), as needed. Alternatively, a sheet formed fromsteel or the like may be sandwiched between outer layers of HDPE to formthe wall of the tank. Plastic molded hemispherical ends may optionallybe utilized. It should be understood that the above bulkhead options mayalso be applied to system 200 described above (and system 500 describedbelow). Preferably, due to the corrosive nature of the materialscontained within the tank, all internal piping is formed from plastic orsimilar non-corrosive materials, with no corrosive metal fasteners orthe like.

In the system 300, wastewater enters the anoxic compartment 304 throughan inlet port 314. The wastewater is mixed in the anoxic compartment304, where facultative bacteria utilize incoming carbon food sources inthe wastewater stream, along with oxygen contained either in the form ofdissolved oxygen or chemically bound in available nitrates, along withfurther nitrites to foster bacterial digestion of the incomingwastewater contaminants and nutrients. Additional recycling and mixingin the anoxic compartment 304 takes place in the form of mixed liquorsuspended solids (MLSS) pumping (via MLSS pump 420 through piping 422)from the bioreactor compartment 306, as in the previous embodiment.Additional mixing and treatment in the anoxic compartment 304 may beimplemented through use of floating media 416; i.e., a moving bedbiological reactor floating and moving through the fluid itself using aconventional submersible mixer.

Wastewater in the anoxic compartment 304 flows by gravity into thebioreactor compartment 306, where additional wastewater treatment isprovided in the form of aeration. Aeration is provided by an electriccompressed air blower assembly 424 or the like, as in the previousembodiment. The blower assembly 424 may be either a regenerative airblower or a positive displacement air pump. Compressed air from theblower assembly 424 is delivered through air piping 426 to at least onesubmerged air diffuser 326. The air diffuser 326 disperses air in theform of air bubbles, which rise to the water surface. The diffuser 326can be either a coarse air or a fine air unit, depending upon the levelof required wastewater treatment.

Aeration from the blower assembly 424 transfers atmospheric oxygen intothe wastewater. Aeration from the blower assembly 424 further providesmixing of the wastewater, fostering growth of the activated sludge. Asin the previous embodiments, the use of a fixed film component, eitherin the form of a stationary plastic assembly or free-floating plasticmedia (shown in FIG. 12 as floating media 416, 418), fosters theformation of the attached growth microorganisms. The combined fixed filmand activated sludge process promotes advanced nitrification andde-nitrification of the wastewater, and ultimately the removal ofnitrogen contaminants.

The MLSS pumping assembly 420 may utilize either an air-lift pump orsubmerged electric pumps, and may have one or more pumps implementedsimultaneously. After treatment in the bioreactor compartment 306,wastewater flows by gravity through a stilling well assembly, as in theprevious embodiment. As in the previous embodiment, the stilling wellassembly reduces, by gravity, the amount of mixed liquor suspendedsolids that will discharge from the bioreactor compartment 306.Wastewater then enters the clarification compartment 308, where themixed liquor suspended solids will settle, by gravity, to the bottom ofa sump assembly, which is preferably sloped, as seen in the previousembodiment. The sloped sump assembly directs settled solids to thebottom of the clarifier chamber 308.

A return activated sludge pump assembly then pumps the settled solidsback to the bioreactor compartment 306 for additional treatment, asdescribed above with reference to the previous embodiment. The clarifiedwastewater or effluent gravity flows up and through an effluentdischarge weir and out of the clarifier compartment 308. The clarifiercompartment 308 is preferably equipped with a surface scum removalassembly that will remove floating scum and solids from the clarifierwater surface, as described above with reference to the previousembodiments.

A membrane filter assembly 342 (or, alternatively, an effluent filter)is used as the clarifier. In FIG. 12, the membrane filter assembly 342is shown as being raised on a platform 333 (preferably formed fromplastic). The membrane assembly 342 includes a manufactured membranefilter unit 344, which may utilize an elastomeric, polymeric, or ceramicmembrane filter media. The membrane unit 344 is modular and can beinstalled in various configurations of the system 300.

The membrane unit 344 uses compressed air from either the bioreactorblower 424 or a separate dedicated membrane blower assembly. Compressedair from the membrane blower 424 provides additional aeration of themixed liquor and further complements nitrification and de-nitrification.The membrane filter assembly 342 discharges effluent or permeate througha permeate discharge pipe 348 and then through an inline ultravioletlight disinfection system 350. The effluent or permeate can bedischarged to a storage tank, which may then be emptied into the localenvironment or reused as reclaimed or recycled wastewater. The treatmentsystem may include a soda ash feed system 440 to adjust pH or additionaltreating agents. Preferably, due to the corrosive nature of thematerials contained within the tank, all internal piping and associatedsupports are formed from plastic or similar non-corrosive materials,with no corrosive metal fasteners or the like. Additionally, a finaleffluent filter may be used prior to pumping through the outlet port.Any suitable type of effluent filter may be used, such as a perviousconcrete manhole-type plate lined with a 20-micron filter sock, a drumfilter or the like. Additionally, phosphorous may be removedbiologically, if required, by binding the phosphorous to themicro-organisms' cellular structures and, subsequently, wasting thephosphorous as part of the wasted sludge.

Access to the horizontal tank wastewater treatment system 300 isprovided through either circular access hatches 356, including risersand removable lids, as described in the previous embodiments, or througha doorway 412. Similarly, as in the previous embodiments and as notedabove, control of the horizontal tank wastewater treatment system 300 isaccomplished through the use of an electronic control panel 410. Thecontrol panel will control influent pumping, bioreactor aeration, MLSSpumping, return activated sludge pumping, membrane aeration,recirculation pumping, and sludge digester aeration. The control panel410 preferably includes both manual and automatic switches, indicatorlights, audible warning horns, visible warning lights, and an optionalauto-dialer mechanism that can notify a manned station in the event of awastewater treatment mechanical problem or report other metered datarequired of the particular system. It should be noted that the controlpanel and blowers may be secured to the top of the outer housing 400 asopposed to being positioned within a separate equipment room 310, asillustrated.

FIG. 13 illustrates a further treatment system 500 including a housing502, which is preferably configured similarly to a conventional septictank. An inlet port 504 with a downpipe assembly is provided for feedingsolid waste into a solids tank 508, as in a conventional septic tanksystem. Preferably, the solids tank 508 includes biological treatment,as described above with regard to the anoxic treatment of the previousembodiments. The solids tank 508 is preferably a cylindrical,steel-reinforced plastic tank. Once treated within this region, thetreated waste gravity flows through an effluent filter assembly 510 intoa pump tank 516 (if pumping is required).

The effluent filter assembly 510 may be supported on vertical supports506 and/or mounted to a baffle wall 512 (which is preferably formed fromplastic) separating the solids tank 508 from the pump tank 516. Accessto the effluent filter assembly 510 for repair or replacement thereofmay be gained via an access hatch 514. The treated waste may then bepumped under pressure generated by the pump 518 through an outlet port520. The system 500 collects wastewater, segregates precipitates fromfloating solids (i.e., sludge and scum, respectively), accumulates,consolidates and stores solids, and provides digestion of organic matterthrough an anaerobic treatment process. The system 500 may also beconfigured to serve as a grease trap (e.g., a FOG separator) in order tocollect and segregate fats, oils and grease from the wastewater stream.

It should be understood that the overall configuration and relativedimensions of the systems 200, 300 and 500 are shown for exemplarypurposes only. The hemispherical bulkhead or end 521 shown on theright-hand side of the tank (in the particular orientation of FIG. 13)could be removed, for example, or a similar hemispherical end piece 523could be added to the left-hand side of the tank, as shown in FIG. 14.In FIG. 14, an access hatch 525 has also been added. It should befurther understood that additional elements, such as access hatches orthe like, may also be incorporated into the end pieces. Such tanks maybe manufactured individually, and the individual tanks may be connectedin the field in series to form larger tanks or a chain of tanks throughelectro-thermoplastic fuse welding or the like. As an example, a pair ofhousings 212 could be manufactured individually, each housing 212 beingapproximately forty feet in length. The pair would then be delivered toa site and the two could be spliced together to form a tank having alength of eighty feet. Such in-field fusing is known in the art ofconveyance pipes and the like.

The steel-reinforced plastic material (which may be steel-reinforcedpolyethylene, polypropylene, carbon reinforced thermoplastic, or othersuitable plastics) used in the tankage affords the wastewater treatmentsystems described above with relatively long service lives, given thecorrosion-resistant nature of the material, as well as providing a meansfor burying the systems, thus providing overall protection from damage.The tankage and plastic internal components have an estimated servicelife of approximately seventy five years. The use of such apre-assembled, portable, steel-reinforced system provides increasedflexibility in the overall design, construction and operation of civilinfrastructure projects.

As noted above, Contech Construction Products, Inc.® of West Chester,Ohio manufactures a steel-reinforced polyethylene (SRPE) pipingpossessing a steel exterior spiral-ribbed banding that is encapsulatedwith a high-density polyethylene plastic, sold under the name DuroMaxx™.FIG. 15 illustrates a partial view of the housing 502, showing thespiral or helically-wound ribs 511 that are encapsulated within thehigh-density polyethylene plastic shell 513. FIG. 16 is a section viewof the wall of housing 502, showing the steel reinforcement ribs 511embedded within plastic 513.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims.

1. A wastewater treatment system, comprising: a hollow, elongate,cylindrical body made from high-density polyethylene, the cylindricalbody having reinforcement ribs formed by a helically wound steel bandembedded in the high-density polyethylene and extending between oppositeends of the elongate cylindrical body; end members extending across andcovering the opposite ends of the cylindrical body, the end members andthe cylindrical body forming a watertight tank defining at least onechamber adapted for treatment of wastewater, the tank being orientedvertically; an inlet pipe extending into the tank adapted for admittingwastewater into the tank, the inlet pipe consisting of a single inletpipe; an outlet pipe extending from the tank adapted for dischargingtreated wastewater from the tank, the outlet pipe consisting of a singleoutlet pipe; first and second partition walls dividing said tank intothree chambers, including: an anoxic first chamber adapted for housingbacteria, said inlet pipe extending into the first chamber, wherein thebacteria is selected from the group consisting of anaerobic bacteria andfacultative bacteria; a second chamber forming a bioreactor adapted forhousing aerobic bacteria; a third chamber forming a clarifier, saidoutlet pipe extending from the third chamber; a first conduit extendingbetween the first chamber and the second chamber for passing partiallytreated wastewater from the anoxic chamber to the bioreactor chamber;and a second conduit extending between the second chamber and the thirdchamber for passing partially treated wastewater from the bioreactorchamber to the clarifier chamber; a first effluent filter disposed inthe anoxic first chamber for filtering undigested organic matter in thepartially treated wastewater before passing the partially treatedwastewater to the bioreactor chamber; a source of pressurized air; anair conduit extending from the source of pressurized air into thebioreactor chamber; an air diffuser connected to the air conduit, thediffuser being disposed in the bioreactor chamber and producing a streamof air bubbles; a fixed film assembly disposed in the bioreactor chamberfor supporting growth of the aerobic bacteria; a return activated sludgepump disposed in the clarifier chamber for feedback of activated sludgefrom the clarifier chamber to the anoxic first chamber for furtherwastewater treatment; and siphon-ejection air lift assembly disposed inthe clarifier chamber for feedback of surface scum from the clarifierchamber to the bioreactor chamber, the siphon-ejection assemblyincluding a air lift pump and needle valve block for air flow rateadjustment.
 2. The wastewater treatment system according to claim 1,further comprising: a baffle wall disposed in the bioreactor chamber;and a stilling well disposed behind the baffle wall, saidsiphon-ejection air lift assembly feeding the surface scum in theclarifier chamber back to the stilling well for further wastewatertreatment.
 3. The wastewater treatment system according to claim 1,wherein said source of pressurized air comprises a blower assembly. 4.The wastewater treatment system according to claim 1, wherein saidsource of pressurized air comprises a mechanical air pumping system. 5.The wastewater treatment system according to claim 1, further comprisingan electronic control unit regulating flow of wastewater between thethree chambers, the feedback of surface scum and activated sludgebetween the chambers, and the inlet and outlet of wastewater into andfrom said tank.
 6. A wastewater treatment system, comprising: a hollow,elongate, cylindrical body made from high-density polyethylene, thecylindrical body having reinforcement ribs formed by a helically woundsteel band embedded in the high-density polyethylene and extendingbetween opposite ends of the elongate cylindrical body; end membersextending across and covering the opposite ends of the cylindrical body,the end members and the cylindrical body forming a watertight tankdefining at least one chamber adapted for treatment of wastewater, thetank being oriented horizontally; an inlet pipe extending into the tankadapted for admitting wastewater into the tank, the inlet pipeconsisting of a single inlet pipe; an outlet pipe extending from thetank adapted for discharging treated wastewater from the tank, theoutlet pipe consisting of a single outlet pipe; a plurality ofvertically extending baffles separating the cylindrical body into aplurality of adjacent compartments adapted for treating wastewater,including a flow equalization and influent pumping compartment, ananoxic compartment, a bioreactor compartment, a clarificationcompartment for effluent polishing, and a sludge digestion compartment;a pump and pump control system disposed in the flow equalization andinfluent pumping compartment for monitoring water levels and pumpingwastewater to the anoxic compartment as needed; the inlet pipe extendinginto the anoxic compartment, the anoxic compartment being adapted formixing incoming wastewater with anaerobic bacteria; an air diffuserdisposed in the bioreactor compartment for aerating wastewater in thebioreactor compartment, the bioreactor compartment being adapted fortreating the wastewater with aerobic bacteria; a pump disposed in thebioreactor compartment for pumping mixed liquor suspended solids fromthe bioreactor compartment back to the anoxic compartment for furthertreatment; a fixed film media assembly disposed in the bioreactorcompartment for fostering growth of aerobic bacteria and resultingformation of suspended growth and attached growth biomass; a stillingwell assembly disposed in the bioreactor compartment; a sloped sumpassembly disposed in the clarifier compartment; thermal insulationdisposed beneath said sloped sump assembly, the thermal insulationincluding closed-cell urethane foam insulation; a return activatedsludge pump disposed in the clarifier compartment for feeding activatedsludge back to the bioreactor compartment for further treatment; adischarge weir disposed in the clarifier compartment; a scum removalassembly disposed in the clarifier compartment for feeding surface scumback to the bioreactor compartment for further treatment; a membranefilter assembly disposed in the membrane compartment; a membrane blowerassembly aerating the membrane filter assembly; a plurality of controlmembers disposed in the membrane compartment, wherein the controlmembers are selected from the group consisting of pressure transducersand float switches; a recirculation pump disposed in the bioreactorcompartment, the recirculation pump being connected to the controlmembers and being configured to optionally pump mixed liquor to themembrane compartment or to the sludge digestion compartment in order tomaintain water levels in the membrane compartment for proper operationof the membrane filter assembly; a diffuser disposed in the sludgedigester compartment for aerating and mixing waste sludge; a pumpassembly disposed in the sludge digester compartment for pumpingsupernatant water from the sludge digester compartment back to thebioreactor compartment for further treatment; and a plurality of accesshatches providing access to each of the compartments.